COPPER ORES. 295 



localities of massive varieties are Ross Island, Kiliarney, 

 Ireland ; Norway, Hessia, Silesia, Siberia, and the Bannat. 

 Fine crystallizations occur at the Bristol copper mine, 

 Conn., in granite ; and also in red sandstone, at ^Cheshire, in 

 the same state, with malachite and heavy spar. Massive va- 

 rieties occur at the New Jersey mines, and in Pennsylvania. 



TETRAHEDRITE.— GRAY COPPER. 



Monometric. Occurs in modified tetrahedrons, and also 

 n compound crystals. Cleavage octahedral in traces. 

 Color between steel-gray and 

 iron-black. Streak nearly as the 

 color. Rather brittle. H=3 — 

 4. Gr=4-75— 5-1. 



Composition : sulphur 26*3, 

 copper 38*6, antimony 16*5, arsenic 7*2, along with some 

 iron, zinc, and silver, amounting to 15 per cent. It some- 

 times contains 30 per cent, of silver in place of part of the 

 copper, and is then called argentiferous gray copper ore, or 

 silver fahlerz. The amount of arsenic varies from to 10 

 per cent. One variety from Spain included 10 per cent, of 

 platinum, and another from Hohenstein some gold ; another 

 from Tuscany 2" 7 per cent, of mercury. 



These varieties give off, before the blowpipe, fumes of ar- 

 senic and antimony, and after roasting yield a globule of cop- 

 per. Dissolve, when pulverjzed, in nitric acid, affording a 

 brownish-green solution. 



Dif. Its copper reactions before the blowpipe and in so- 

 lution in nitric acid, distinguish it from the gray silver ores. 



Obs. The Cornish mines, Andreasberg in the Hartz, 

 Kremnitz in Hungary, Freiberg in Saxony, Kapnik in 

 Transylvania, and Dillenberg in Nassau, afford fine crystal- 

 lizations of this ore. It is a common ore in the Chilian 

 mines, and it is worked there and elsewhere for copper, and 

 often ako for silver. 



Bournonite contains sulphur 203, antimony 26*3, lead 408, copper 

 12.7. Its crystals are modified rectangular prisms, of a steel-gray color 

 and streak, and are often compounded into shapes like a cog-wheel, 

 whence it is called wheel-ore. H=25 — 3. Gr=5766. From the 

 Hartz, Transylvania, Saxony, and Cornwall. Another allied ore, con- 

 aining 47 per cent, of antimony, is called antimonial copper ; it oc- 



Describe gray copper ore. Mention its composition and blowpipe 

 characters. How is it distinguished from silver ores ? 



